Starting July 1, 2017, at least 1 of every 15 bulk milk tankers will be tested by the FDA for the presence of tetracycline. While routine testing for tetracycline is not a novel concept, the new tests will be able to detect tetracycline at levels even lower than the tolerance level of 300 parts per billion.
Hoof trimmers routinely use tetracycline powder to treat hoof lesions such as digital dermatitis and hairy heel wart. With the implementation of the Veterinary Food Directive (VFD) on January 1st, these previously over-the-counter drugs now require veterinary authorization and extra-label usage is strictly prohibited.
This means that dairy farmers require a valid Veterinary-Client-Patient-Relationship (VCPR) in order to obtain and use tetracycline on the farm. According to Dr. Gerard Cramer, a hoof care specialist with the University of Minnesota, "applying 2 grams or less of tetracycline per lesion for a maximum of two lesions per cow will not cause a violative residue in individual cows." If your hoof trimmer is applying a larger dose, a longer meat and milk withdrawal regime is warranted.
It is important to have a conversation with your the hoof trimmers on your farm to prevent violative residues. While hoof trimmers are accustomed to pouring on applications of unmeasured doses, 2 grams of tetracycline powder roughly equates to 1/2 of a teaspoon of tetracycline powder.
Furthermore, new research out of Iowa State University indicates that heavy topical antibiotic treatments may actually delay healing of the hoof tissue and can actually prolong lameness. The study led by Dr. Jan Shearer found that the best treatment is usually to clean and trim any dead tissue from the affected area and to simply place a block on the opposite claw. Severely lame cows should be housed in a clean, dry, and well bedded area, where they don't have to walk far to access feed and water.
Dr. Shearer does not recommend the bandaging of lesions following trimming. "The problem with wrapping is that within a matter of hours, the wrapping becomes very contaminated with footbath solution and organic matter. A footbath contaminated manure wrap isn't likely beneficial." Shearer points out that the lack of oxygen also prevents wound healing.
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